The American Civil Liberties Union (ACLU) announced Monday that it had filed a lawsuit in conjunction with the Southern Poverty Law Center (SPLC) against a Florida sheriff’s office for unlawfully detaining and nearly deporting a U.S citizen.

Peter Sean Brown was born in Philadelphia and has lived in Florida for the last 10 years. According to the complaint, Brown reported to the Monroe County Sheriff’s Office in April for violating his probation for a low-level marijuana offense and was subsequently detained longer than was required at the request of Immigration and Customs Enforcement (ICE).

ICE believed Brown was a Jamaican undocumented immigrant of the same name, and was intent on deporting him. Despite his repeated pleas that he was a U.S. citizen with a birth certificate and a Florida driver’s license, Monroe County jail officers told him he was being sent to a country he had only been to once on a cruise.

“I am and have always been a citizen of the United States,” Brown said in a video released by the ACLU. “I did not even realize what ICE was at the time and reading through it I realized it had something to do with immigration, and at that point, I made a comment of, ‘There must’ve been a mistake.'”